Report for NSWSKC – Definition of a Sea Kayak [8]

This discussion paper attempts to answer the question, “What is a safe sea kayak?”

The NSW Sea Kayak Club decided to form a committee to make this definition out of concern for the safety of all sea kayakers.

Our first concern is that with the increasing popularity of sea kayaks in recent years, organisers of events such as the Hawkesbury Classic, have included a “sea kayak” class in races without an adequate measurement and construction specification. Some competitors may attempt to take line honours by entering specially built or modified craft which are not sea kayaks in the accepted sense, but ultra light and flimsy racing boats. This does not present a problem in itself, but if such a craft was sold to an unsuspecting person who subsequently went to sea in it, then the results could be disastrous. A clear definition of a safe sea kayak may help to prevent this.

Secondly as more people take up sea kayaking, a recommended equipment list for kayaks operating in open waters is needed. This is personal equipment or boat fittings over and above the basic design and construction requirements for sea kayaks, but which contribute to the safety of the paddler.’

It is hoped that these two initiatives will encourage self-regulation by the sea kayaking fraternity. If this does not happen, then some over-zealous government regulation may eventually be enacted (as is the case in France) seeking to protect individuals from themselves, to the detriment of the freedom which draws people to sell kayaking in the first place.

What is a Sea Kayak?

“A sea kayak is a kayak equipped and constructed to be operated on the open sea.”

However to come up with a definitive description of a sea kayak is a difficult task, because each paddler will have an opinion gained through experience as to what constitutes a good sea kayak. The type of paddling carried out and the conditions prevailing in areas visited will all influence that opinion.

We can define certain characteristics of a canoe which allow us to call it a kayak and we can define some special features of a sea kayak which will distinguish it from a sprint, marathon, slalom, polo, white water racing, surf, or touring boat, but this does not mean that a kayak designed for touring will not make a good sea kayak or that a specially designed “sea kayak” will prove to be a seaworthy craft.

Most of the currently popular sea kayaks are based on traditional Greenland native designs which have been modified to accommodate larger European body sizes, however there are several successful designs (the well known and respected Klepper series of kayaks for example) which do not conform to the “normal” long slender design characteristics of the Greenland model. So appearance alone can’t be used to define a sea kayak. This leaves performance as the best way to approach the question.

What Makes a Safe Sea Kayak?

Kayaks which meet ALL of the following performance, design, and construction criteria may be considered a “safe sea kayak”:

  • Be strongly constructed to withstand the pressures and bending forces associated with waves
  • Have a reasonable turn of speed
  • Have comfortable seating with adequate leg and foot room
  • Be fitted with decklines for rescue or towing
  • Have buoyancy material in both ends of the hull space (in addition to bulkheads or pod) to support the total weight of the boat, gear, and paddler when the hull is completely flooded
  • Have minimum cockpit volume
  • Be equipped for removing water from the boat while at sea
  • Be directionally stable so that it is controllable under adverse conditions without the use of a rudder or skeg
  • Be easy to recover from a capsize while at sea, both by the paddler alone, and with the help of others
  • Have minimal windage, to aid control in high winds
  • Remain stable when tipped to one side (good dynamic stability)

Design and Construction Specifications

The following are some more specific guidelines on construction and fittings for sea kayaks.


Is dependant upon the materials used for construction however for fibreglass kayaks a lower limit of 3 kg/metre of length could be taken as a guide.

Hull Shape

Cross section – Hull shapes should conform to the generally accepted forms: U shaped, Vee shaped, Hard-chine, Multi-chine, Half round (or combinations of these shapes.) Flat-bottomed hulls are not acceptable due to the low dynamic stability of this hull shape.

Where half-round hull shapes are used, the Stability Ratio (SR) should be greater than 5:1

Where Stability Ratio = (Beam on the water-line) : (Draught of the loaded boat), e.g., SR = 50cm : 10cm = 5:1

Whatever hull shape is used, the centre of gravity should be kept as low as possible, and the centre of buoyancy should be as close to the maximum beam as possible.

Profile – Curvature of the keel or “rocker” should be such that directional stability is not dependant on additional equipment such as rudders or fins.

Construction Materials

Any material approved by marine insurers and bodies such as the MSB for small boat building is acceptable for kayak construction.

Note: The relevant Standards Association of Australia standard should be consulted where applicable.

For hard shell kayaks materials include:

  • Solid wood
  • Plywood
  • Veneers
  • G.R.P
  • Kevlar
  • Carbon fibre composites
  • Foam sandwich
  • Aluminium and other light alloys
  • Polyethelene (must have an internal stiffening frame or “Pod”)

For soft shell kayaks use strong, flexible, waterproof materials, such as:

  • Canvas
  • Rubberised canvas
  • Hypalon-nylon
  • Kordura

Waterproofing may be either intrinsic to their manufacture (eg calendaring) or through the application of waterproofing compounds. All joints should be sealed to stop water penetration.

Frames should be constructed from marine grade materials such as:

  • Solid wood
  • Laminated wood
  • Plywood
  • Light alloys
  • Composite materials

Where frames are not used, such as in an inflatable kayak, multiple separate airchambers are to be used so that a single puncture does not deflate the whole craft.

Adhesives – must be waterproof marine types, such as:

  • Resorsinol Formaldehyde
  • Epoxy resin
  • Urea Formaldehyde
  • Polyester resin
  • Polyvinyl resin

Note: Polyester and polyvinyl resins can only be used for bonding to the same materials.

Fastenings And Fittings – Must be salt-water corrosion resistant marine types, such as:

  • Stainless steel
  • Brass and Bronze
  • “Monel”
  • Aluminium
  • Plastic

Fastenings made from different metals should not be placed together, unless a corrosion inhibitor is used.

Fixed or Positive Buoyancy

The kayak must have some form of positive buoyancy installed. The flotation material must be positioned within the hull space, so that the kayak remains controllable (the boat can be paddled) in the event of a leaking hatch or damaged skin flooding the hull.

This material can be a combination of:

  • Foam (polystyrene in block form or polyurethane “blown” in situ)
  • Watertight bulkhead(s)
  • Air-filled bags eg waterproof gear bags or buoyancy bags
  • “Pod” type cockpit construction eg “Puffin”

To calculate the amount of buoyancy required for a given boat and paddler use the following guide:

First calculate displacement (eg single kayak):

75.0 kg paddler + 25.0 kg sea kayak + 1.0 kg paddle + 75.0 kg supplies and equipment = 176.0 kg Total displacement

Then find the volume of flotation material required given that 1 cubic metre of air will displace 1000 kg of water.

Minimum required flotation = 176 kg : 1000 kg = 0.176 m3 flotation

Note: 0.038 kg polyurathane (expanding resin) foam will expand to provide 1 kg buoyancy.

When considering the type of flotation material to use, a combination of blown in situ or block foam, and air filled bags would provide the most versatile solution, remembering that any waterproof gear bags stowed within the hull will act as buoyancy in the event of flooding. If possible the hull space should be completely filled with flotation material to minimise the amount of water within the hull. (You risk losing the kayak and possibly your life if the hull compartments are empty).

Pumps and Bailers

At least two methods of emptying water from a swamped kayak should be available.

The primary system such as a hand or foot operated pump, dinghy self bailer, or electric bilge pump must allow operation under rough conditions when the paddle is being used to stay upright. Any system used should have a capacity of at least 25 litres per minute (Some pump systems can be rigged with a long inlet tube and “strum box” to allow pumping from hull compartments or other boats).

Note: Hand operated pumps may not be suitable for unassisted use.

A secondary bailer, such as a hand held pump, a cut-down plastic bottle, or plastic jug etc. should always be carried, tied to the boat by a suitable length of cord. A sponge for sopping up small amounts of water is also desirable.


Decklines (or lifelines) should be made of at least 6mm braided rope, firmly fixed to the deck at approx. 800mm spacing.

Recommended Equipment and Fittings for Opens Sea Operation

Sea kayaking, more than most other branches of canoeing, is completely unforgiving, the sea can be very dangerous. Well chosen equipment, careful planning, awareness of the limitations of yourself and your boat and a sound understanding of the environment in which you will be paddling will all contribute to the safe enjoyment of sea kayaking.

The following guide has been prepared from the collective knowledge of many experienced seafarers and sea kayakers, but it is not a substitute for personal experience. You have the final choice; if you are prudent, sensible, and well practiced you will get great pleasure from going to sea in a kayak; if you are not you will probably die or worse, cause someone else to die trying to rescue you.

Personal Flotation Devices or PFD’s – By law a PFD to SAA standard 1499, 1512 or 2260 must be worn at all times when paddling on open waters. Even if you are on enclosed waters remember that it is much easier for searchers to find a floating body.

A Spray Deck – is recommended to prevent the cockpit flooding and to keep the legs warm (to avoid hypothermia) in colder areas.

Compass And Chart – should always be available The paddler should carry one compass (for hand bearings) and have another steering compass fixed to the boat for use “hands-free”. The steering compass should be installed with non-ferrous fittings. All magnetic materials (either in gear or part of the kayak’s deck fittings) should be kept well away from the compasses. A chart holder (eg elastic cord attached to the deck) will keep charts, in a waterproof map case, ready for use whilst paddling.

Tow Rope – made from floating ski tow rope, should be rigged and carried on the deck, (7 metres overall in length, including a section of elastic cord as a shock absorber. Terminate the rope with stainless steel snap links for quick attachment).

A Drogue – should be carried for extended journeys in open sea conditions. (The tow rope could also serve a similar duty by trailing in a loop from the stern or bow).

Communication Equipment – the minimum requirement is:

  • A pea-less whistle which is designed for use in the water (Many PFD’s come with a whistle attached)
  • A waterproof, shatterproof, signalling mirror
  • A waterproof torch
  • A small portable radio for weather reports

For extended journeys, or journeys in more remote areas the following equipment should be considered:

  • Flares (Parachute or hand-held red flares, hand-held smoke flares as set out in the MSB’s Safe Boating Handbook)
  • Dye marker
  • VHF or 27mz marine radio

Note: Boating safety regulations outside NSW may require that special equipment be carried by all craft venturing offshore. You should check for any local regulations before setting off on interstate or overseas trips.

Rudders And Skegs – should be solidly constructed of marine grade materials such as aluminium, stainless steel, plastics, marine ply etc. “Beaching” type rudders or skegs are preferred. That is, they can be raised or lowered from the cockpit. If not the rudder must be protected from damage during launching or landing in surf or impact on submerged rocks.

Lights – for operation at night, the minimum requirement is for a white light (electric torch or lantern) which can be shown in time to prevent a collision. Note: See MSB handbook for details of legal requirements.

Drinking Water – consumption is dependant upon exertion, air temperature and body size, but at least four litres per person per planned day (plus one days reserve per person) should be carried in strong sealed containers. (used wine cask bladders are excellent).

A First Aid Kit – conforming to the AYF Basic First Aid Kit specification should be carried.

Boat Repair Kit – this will depend upon the length and severity of the journey, but at least the following should be carried:

  • Roll of 50mm wide “duct” tape
  • Knife (preferably a “Swiss Army” type.)
  • Length of copper wire
  • Spare rudder cable
  • Pliers

On longer trips you should carry materials to effect permanent repairs to the boats or equipment eg fibreglass and resin, solvents and abrasives.

Spare Paddle – can be a single ended canoe-type paddle or a jointed double-ended paddle and should be easily accessible but stowed so as to remain in position under rough conditions.

Clothing – depends on conditions. You can be sure of one thing though; no matter how hot it is, you may need to get warmly dressed very quickly, and no matter how cold it was when you started your paddle, you could find yourself overdressed and overheating. The following list should be minimum in any Australian waters:

  • Hat
  • Long-sleeve shirt
  • Tee-shirt or singlet
  • Sun Blockout (15+)
  • Cag or spray jacket
  • Neoprene booties
  • Thermalwear
  • Swimming costume
  • Shorts

Optional sleeveless wetsuit (Long or Short John type)

Note: Spare clothing should be carried in a waterproof gear bag ready for or use at any time.


  1. Dalton, Teki ed. “Sea Safety” Canberra: Dept. of Transport and Communications and Overseas Telecommunications Commission, 1988.
  2. Dean G.A. in Bushwalking and Camping (Paddy Pallin)
  3. Dowd, John “Sea Kayaking: a manual for long distance touring.” Revised ed. Vancouver: British Columbia, Douglas & McIntyre, 1988.
  4. Goodman, Frank R. 2. “Design and Selection of Equipment,” and 3. “Canoe Construction and Maintenance.” No date. Pamphlets published by The British Canoe Union. Available from BCU Supplies, 70 Brompton Road, London, SW3 1DT.
  5. Hutchinson, Derek. “Derek C. Hutchinson’s Guide to Sea Kayaking.” Seattle: Pacific Search Press, 1985.
  6. Hutchinson, Derek. “Sea Canoeing.” 3rd ed. London: A & C Black (Publishers) Ltd., 1985.
  7. Lamont P. “Experimental Flooding of Two Sea Kayaks” unpublished report BCU 1989
  8. Maritime Services Board of N.S.W “Safe Boating Handbook.”
  9. Newsletter of the Advanced Sea Kayak Club
  10. Newsletter of the Tasmanian Sea Canoe Club
  11. Samson, Jorgen “Canoe Design” in “Canoeing Complete.” Revised edition. London: Kaye & Ward Ltd., 1976
  12. Winning D. “Sea Tiger Report” unpublished for BCU 1990

With the exception of the club newsletters and BCU pamphlets, all of these publications should be available from your local library. Some specialty canoe shops carry some titles from time to time.